1. Technical Field
The present invention relates to methods and apparatus for testing the integrity of the walls and connecting joints of a tubing string to determine the presence of leaks in the pipe walls or joints prior to or after insertion of the tubing string into a bore hole.
2. The Relevant Technology
In typical oil and gas exploration efforts, an initial search is made to identify various geographical formations that are believed to be potential sources of a desired product. When such geographical formations have been located and identified, one or more exploratory wells are drilled in an effort to ascertain aspects such as the quantity, quality, and accessibility of any materials that may be present. Once it has been determined that it is economically viable to recover the discovered materials, a well, or well hole, is drilled in order to facilitate access to those materials.
After the well hole has been drilled, a casing is inserted into the ground and cemented in position in the well hole. Typically, the casing comprises a series of hollow members connected end to end in order to form the long, hollow casing pipe. After the casing has been secured in position, a production pipe or “string” of tubing is inserted down through the casing. Like the casing, the production pipe comprises a series of hollow members connected end to end in order to form the long, hollow production pipe that can extend downward into the reservoir or area where the gas, oil, or other materials are located. In some installations, the lower portion, or other selected portions of the production pipe are perforated so that the oil, gas, or other materials can flow into the production pipe and up to a wellhead connected to the production pipe and located at the surface. In many cases however, the natural pressure of the material desired to be recovered is not sufficient to ensure that the material flows to the surface at an adequate rate.
Accordingly, many gas and oil rigs and recovery systems include one or more well pumps, such as positive displacement pumps, configured and arranged to aid in moving the materials to the surface relatively more quickly. Typically, such well pumps include a pump discharge line, or other discharge connection, that is connected to the lower end of the production pipe. A check valve is provided in the pump discharge line so that backflow into the well pump from the discharge line and/or production pipe is prevented. The well pump further includes a suction connection to which is attached a suction line that extends into the reservoir or area where the gas, oil or other materials are located. In other cases, the well pump is a submersible type, so that the suction connection is submersed in the material to be pumped, and no suction line is required.
In operation, the well pump directs a flow of oil, gas or other materials into the production pipe after another pump located at the surface has cycled. Similar to the well pump, the surface pump may be a displacement type pump. When the gas, oil, or other material reaches the surface, those materials are then directed through a wellhead and into the production system.
Prior to beginning production through a production pipe, it is important to conduct pressure tests on the production pipe, including the pipe walls and all connection joints, to determine whether any leaks exist. If a leak exists at a joint between two sections of the production pipe, for example, the joint must be tightened, sealed, replaced, or otherwise repaired to ensure that the production pipe functions properly. Any such leaks in the production pipe need to be mended so that sufficient pressure can be maintained within the production pipe to allow the gas, oil, or other material to flow up to the surface without leaking out of the production pipe and into the casing.
The present invention provides methods, systems, and devices for quickly and reliably conducting pressure tests on production pipes either before or after the production pipes have been installed in a well basing. Nevertheless, the subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.